Wireless communications operating according to a predetermined protocol have gained worldwide popularity. The advantages of the wireless medium include the capacity to address broad geographic areas without expensive infrastructure development such as running cables. The broadband wireless access industry often is guided by IEEE standard 802.16 for wide area networks.
Worldwide Interoperability for Microwave Access (WiMAX) is a wireless communications technology for providing wireless data based on the IEEE standard 802.16. A WiMAX network provides an alternative to cabled access networks, such as a digital subscriber line (DSL). In addition, the WiMAX technology may provide fixed, nomadic, portable, and mobile wireless broadband connectivity to a base station.
The IEEE standard 802.16 supports a multicast and broadcast service (MBS), which can provide content data to a plurality of users who desire to receive a same service in the WiMAX network. For example, the content data may be movies, games, or TV programs, and is usually stored on one or more MBS servers. A mobile station (MS), such as a mobile phone or a laptop computer, subscribing to an MBS may receive MBS data that includes the content data and control information, through access to one or more base stations (BSs) in the WiMAX network.
For example, the BSs may each transmit the MBS data based on a same multicast connection identifier (MCID). Typically, the BSs are in a same MBS zone. An MBS zone is a set of BSs in a geographic area which use the same MCID to transmit MBS data. The advantages of the MBS zone include that the MS may receive signals from ones of the BSs in the MBS zone simultaneously. This would provide a diversity gain for the received signals. Further, the MS may receive the MBS data from any one of the BSs in the MBS zone without requiring a handover.
Typically, the MBS data is transmitted in a plurality of data frames. For example, according to the IEEE standard 802.16, a data frame may include a downlink map (DL-MAP), an MBS map (MBS-MAP), a plurality of MBS data bursts including the content data, and other information. The DL-MAP includes an MBS-MAP information element (MBS-MAP-IE), which indicates in that data frame a location of the MBS-MAP based on, e.g., symbol offsets, and provides information for the MS to perform synchronization with the MBS-MAP.
The MBS-MAP includes one or more MBS data information elements (MBS-DATA-IEs) or extended MBS data information elements (Extended MBS-DATA-IEs), collectively referred to herein as MBS-DATA-IEs, which provide access information for MBS data bursts in the plurality of data frames. For example, the MBS data is typically transmitted on a plurality of logical channels, and each of the MBS-DATA-IEs provides a connection identifier for one of the plurality of logical channels. Also for example, a first one of the MBS-DATA-IEs indicates in the plurality of data frames a location of an MBS data burst corresponding to a first one of the logical channels based on, e.g., frame and symbol offsets. The first one of the MBS-DATA-IEs also indicates in the plurality of data frames a location of a next MBS-MAP including information relating to the first one of the logical channels.
FIG. 1 illustrates a conventional MBS data structure 100, according to the IEEE standard 802.16. The MBS data structure 100 includes a plurality of data frames 101, which are transmitted from a BS to an MS. For example, the BS may deliver content of a first TV program on a first logical channel, content of a second TV program on a second logical channel, and content of a movie on a third logical channel. For convenience of illustration, only MBS-MAP-IEs, MBS-MAPs, MBS-DATA-IEs, and MBS data bursts that relate to the first, second, and third logical channels are labeled on the MBS data structure 100.
Referring to FIG. 1, the MBS data structure 100 may include MBS-MAP-IEs 102, 104, and 106, MBS-MAPs 112, 114, and 116, and data bursts 122-i (i=1, 2, 3), 124-i (i=1, 2), and 126-i (i=1, 2, 3). The MBS-MAPs 112, 114, 116 may further include MBS-DATA-IEs 132-i (i=1, 2, 3), 134-i (i=1, 2), and 136-i (i=1, 2, 3), respectively. The MBS-DATA-IEs 132-1, 134-1, and 136-1 and the MBS data bursts 122-1, 124-1, and 126-1 relate to the first logical channel. The MBS-DATA-IEs 132-2, 134-2, and 136-2 and the MBS data bursts 122-2, 124-2, and 126-2 relate to the second logical channel. The MBS-DATA-IEs 132-3 and 136-3 and the MBS data bursts 122-3 and 126-3 relate to the third logical channel.
For example, the MBS-MAP-IEs 102, 104, and 106 indicate locations of the MBS-MAPs 112, 114, and 116 in the data frames 101, respectively. For the first logical channel, the MBS-DATA-IEs 132-1, 134-1, and 136-1 provide a first connection identifier, and indicate in the data frames 101 locations of the MBS data bursts 122-1, 124-1, and 126-1, respectively. In addition, the MBS-DATA-IE 132-1 indicates in the data frames 101 a location of the next MBS-MAP 114. The MBS-DATA-IE 134-1 in the MBS-MAP 114 further indicates a location of the next MBS-MAP 116.
Also for example, for the second logical channel, the MBS-DATA-IEs 132-2, 134-2, and 136-2 provide a second connection identifier, and indicate in the data frames 101 locations of the MBS data bursts 122-2, 124-2, and 126-2, respectively. In addition, the MBS-DATA-IE 132-2 indicates in the data frames 101 the location of the next MBS-MAP 114. The MBS-DATA-IE 134-2 in the MBS-MAP 114 further indicates the location of the next MBS-MAP 116.
Further for example, for the third logical channel, the MBS-DATA-IEs 132-3 and 136-3 provide a third connection identifier, and indicate in the data frames 101 locations of the MBS data bursts 122-3 and 126-3, respectively. In addition, the MBS-DATA-IE 132-3 indicates in the data frames 101 the location of the next MBS-MAP 116. All of the above-described location indications are represented by the dashed lines and arrows in FIG. 1.
The MS may receive the content on one of the three logical channels by reading the data frames 101. For example, if the MS wants to receive the content on the first logical channel, the MS may read the MBS-MAP-IE 102. Based on the MBS-MAP-IE 102, the MS may know when to read the MBS-MAP 112. Based on the MBS-DATA-IE 132-1 in the MBS-MAP 112, the MS may further know when to read the MBS data burst 122-1 and the next MBS-MAP 114. Similarly, based on the MBS-DATA-IE 134-1 in the MBS-MAP 114, the MS may know when to read the MBS data burst 124-1 and the next MBS-MAP 116, and based on the MBS-DATA-IE 136-1 in the MBS-MAP 116, the MS may further know when to read the MBS data burst 126-1. In this manner, the MS may read the MBS data bursts 122-1, 124-1, and 126-1 for the content delivered on the first logical channel. Similarly, the MS may read the MBS data bursts 122-2, 124-2, and 126-2 for the content delivered on the second logical channel, or the MBS data bursts 122-3 and 126-3 for the content delivered on the third logical channel.